Sliding vane pump



Dec. 26. 1961 H. K. J. VAN DEN BUSSCHE 3,

SLIDING VANE PUMP Filed July 15, 1959 2 Sheets-Sheet 1 AGENT H. K. J.VAN DEN BUSSCHE Dec. 26, 1961 SLIDING VANE PUMP Filed July 13, 1959 2Sheets-Sheet 2 ware Filed July 13, N59, Ser. No. 826,576 Claimspriority, application Netherlands Aug. 15, 1958 6 Claims. (Cl. 103-136)The invention relates to pumps and pertains more par ticularly to asliding vane pump comprising a housing, a rotor having substantiallyradial slots, and radially slidable vanes in these slots.

The invention relates in particular to a sliding vane pump in which eachslot space, i.e., the space formed in each rotor slot beneath the vaneaccommodated therein, communicates with the pump space which, relativeto the direction of rotation of the rotor, is situated in front of theassociated vane.

Since liquid can flow through these communication passages into and outof the slot spaces when the vanes in the slots move outwards and inwardsrespectively, the pressure prevailing in each slot space will besubstantially equal to the pressure in the pump space which, relative tothe direction of rotation of the rotor, is situated in front of theassociated v-ane.

The centrifugal force caused by the rotation of the rotor forces thevanes outwardly to make contact with the inner wall of the housing. Thisthrust is further increased in that the communication passages enablethe pressure prevailing in the pump space in front of each vane to betransmitted into the relative slot spaces.

When high rotor speeds are used in pumps where the slot formed betweenthe outer wall of the rotor and the inner wall of the housing in theregion where the highpressure zone of the outlet port adjoins thelow-pressure zone of the inlet port is only of narrow width, erosion isfound to occur in the slots in the part nearest to the center line ofthe rotor, which erosion, judging from its outward appearance, isattributable to cavitation.

The primary object of the invention is to prevent erosion in the slotsof a pump of the sliding-vane type. Another object of this invention isto minimize excessive wear in sliding-vane pumps, which wear occurs inthe form of cavitation in the bottom of the slots in which the vanes arehoused. This is attained by establishing communication between each slotspace, the vane accommodated in the slot being in the slid-in position,and the pump space which, relative to the direction of rotation of therotor, is situated behind the associated vane.

Tests with the sliding vane pump according to the invention have shownthat the said erosion is entirely suppressed by the arrangement made. Itwas also found that the previous wear of the inner wall of the housingin the region where the high-pressure zone of the outlet port adjoinsthe low-pressure zone of the inlet port was reduced to nil.

Moreover, the wear of the outer edges of the vanes had been considerablyreduced.

The said communication passages between the slot spaces and the pumpspaces situated behind the relative vanes are preferably constituted bygrooves or channels States atet which are provided in the vanes andcooperate with the grooves-or channels arranged in the walls of therelative slots when the vanes are in the slid-in position.

In a preferred embodiment of the sliding vane pump according to theinvention the back of each vane is provided with a substantially radialgroove which communicates with the pump space which is situated,relative to the direction of rotation of the rotor, behind theassociated vane, while the slot wall'cooperating with the said vane wallis provided with a groove which communicates with the slot space andcommunicates with the other groove only when the vane is in the slid-inposition.

In a second preferred embodiment of the sliding vane pump according tothe invention at least one of the side or end walls of each slot isprovided with two substantially radial grooves, one of the groovescommunicating with the slot space, and the other communicating with thepump space which, relative to the direction of rotation of the rotor issituated behind the associated vane, while a substantially radial grooveis provided in the adjacent side or end wall of the vane whichcooperates with the grooved side or end wall of the slot, which grooveonly communicates with both grooves provided in the side or end wall ofthe slot when the vane is in the slid-in position.

The invention will be further elucidated with reference to the drawings,wherein:

FIGURE 1 is a cross-sectional view of a sliding vane pump according tothe invention;

FIGURE 2 is a longitudinal sectional view taken along the line IIII ofFIGURE 1;

FIGURE 3 is part of a longitudinal sectional view of another embodimentof the sliding vane pump according to the invention;

FIGURE 4 is part of a second longitudinal sectional view of the pumpshown in FIGURE 3; and

FIGURE 5 is part of a cross-sectional view taken along the line V--V ofFIGURE 3.

The sliding vane pump shown in FIGURES l and 2 is of the double-actingtype, viz it has two inlet ports 1, 1' and two outlet ports 2, 2,disposed in a symmetrical arrangement in the housing 3. I

In the housing 3 is mounted the rotor t which is supported in thehousing by means of the shaft journal 5 and the shaft 6 and is driven bymeans of shaft 6 in the direction shown in FIGURE 1.

The rotor is provided with a plurality of radial slots 7, each of whichaccommodates a vane 3 slidably mounted therein. The inside of thehousing is so shaped that a pump space A, crescent-shaped incross-section, extends on the one hand over the space between thisinside wall of the housing and the outer wall of the rotor 4, and on theother over the space between an inlet (1 and 1') and an associatedoutlet (2 and 2). Since the pump shown in FIGURES 1 and 2 is adouble-acting one, it has two pump spaces A and B of this type which aretraversed by the parts of the vanes 8 protruding from the rotor 4 andare so divided into separate spaces that direct communication can neverbe established between the inlet 1 and the outlet 2 (or 1 and 2) andbetween the inlet 1 and the inlet 2' (or 1 and 2) on rotation of therotor. The flow created by rotation of rotor 4 in the housing 3 isindicated by arrows in the inlet ports 1, 1' and the outlet ports 2, 2'.

One wall of each slot 7 is provided with a narrow conduit, fluidpassageway or groove 9 extending from the bottom of the slot 7 to thepart of the pump space A or B which, relative to the direction ofrotation of the rotor is situated in front or on the downstream side ofthe vane 8 accommodated in slot 7. Alternatively, the groove 9 may beformed in the adjacent face of the vane and extend entirely across it inthe same direction. Thus, in all positions of the vane 8 the slot spacebelow the vane 8 communicatesswith the pump space A or B in front of thevane.

Each slot 7 is also provided with a narrow groove 10, extending from thebottom of the slot '7 to halfv/ay along the height thereof in the wallopposite that of the vane to approximately half-way along the heightthereof. The placement and lengths of the grooves 19 and 11 are suchthat the grooves only communicate with each other when the vanes are inthe slid-in position, viz in the position in which the vanes pass thedam 12 between the outlet port 2 and the inlet port it and the dam 13between the outlet port 2 and the inlet port 1. In all other positionsof the vanes this communication is broken. in other words, the pumpspaces on both sides of each vane communicate through the associatedslot space when the associated vane is completely slid into theassociated slot. in all other positions the said pump spaces do notcommunicate with each other, but whereas the pump space situated behindcach vane is not in communication with the associated slot space, thepump space situated in front of each vane is in communication with theassociated slot space.

The pump is provided with supply and discharge lines (not shown)connected to the ports, 1, 1', 2 and 2 and is also coupled by means ofthe shaft 6 to a driving motor (not shown).

When the pump is in operation the rotation of the rotor 4 and themovements of the vanes 8 cause liquid to be pumped from the inlet ports1 and 1' to the outlet ports 2 and 2', respectively. During thisrotation each slot space is in constant communication with the pumpspace situated in front of the associated vane. The result is that firstof all the movement of the vanes in the slots is not hampered bypressure variations occurring in each slot space as a result of the factthat the volume of each slot space is periodically increased anddecreased, while moreover a thrust is set up, forcing the vanes 8against the inner wall of the housing 3.

A vane passing the outlet port 2 is gradually forced inwardly by theinner wall of the housing and kept in this inward position by the innerwall in its travel to the next inlet port 1. The clearance between therotor 4 and the inner wall of the housing 3 is as small as possible atthis point, i.e., where the dam 13 is located, in order to reduceleakage of liquid from the high-pressure outlet port 2 to thelow-pressure inlet port 1 to a minimum.

Accordingly, when the vanes pass the dam 13 each vane is almostcompletely slid into the associated slot 7, and the ends of the groovesit) and 11 overlap in this position. As a result, communication isestablished between the pump spaces which, relative to the direction ofrotation, are situated in front of and behind the vane, through thegroove 9, the associated slot space 7, the groove 16, the overlapopening 14 and the groove 11.

It should be observed that, when passing the dam 12 on their travel fromthe outlet port 2 and the inlet port 1, the vanes S are also pressedinto the position in which they are substantially slid in, so thatcommunication is established between the pump spaces situated in frontof and behind the associated vanes, in the same way as described above.

It is found that the attack of the dams 12 and and of the walls of theslot spaces 7 in the case of sliding vane pumps not provided with thegrooves it? and 11, is completely suppressed in the sliding vane pumpaccording to the invention.

The explanation of absence of gailing between the edges of the vanes Sand the dams 12 and 13 in the sliding vane pump according to theinvention is as follows. When a vane 8 in the slid-in position movesfrom an outlet port (2, 2) to an inlet port (It, 1) it has to entrainthe liquid present in the narrow slit between the rotor 4 and thehousing 3,'but the flow of liquid in this narrow slit is necessarilyaccompanied by a great diiterence in pressure, i.e., when the vane 8 is,for example, half-way on its travel between an outlet port and an inletport, the pressure behind the vane is appreciably lower than that in theoutlet port, and the pressure in front of the vane is appreciably higherthan that in the inlet port. The high pressure in front of the vane istransmitted through the groove 9 to the slot space 7 under the vane and,if grooves 10 and 11 are absent, presses the outer edge of the vane withsuch force against the inner wall of the housing that galling occursbetween the edge and the wall. If, however, the slot space 7 alsocommunicates with the pump space behind the vane through the grooves 10and i1 and the overlap opening 14, the pressure between the pump spaceson both sides of the vane will be at least partially equalized and noexcessive pressures will prevail in the slot space 7, so that there isno galling. This advantage is admittedly obtained at the expense offluid leaking through from the outlet port to the inlet port through theslot space, although the quantity of fluid leaking through is verysmall.

No obvious explanation can be given as to why the attack of the wall ofthe slot spaces under the vane is suppressed by the said provision. Itis probably due to the fact that the magnitude of the sudden pressurefluctuations in the slot space 7 decreases when the latter approachesthe inlet port. In the known construction there is then a maximumsubatmospheric pressure behind the vane, whereas the pressure in frontof the vane is almost equal to the pressure in the inlet port. If thelow pressure prevailing behind the vane can exert its influence throughthe clearance between vane and slot wall (egg. in the case of avibrating movement of the partition in its slot) in the slot space wherethe centrifugal force causes a liquid pressure which is in any caselower than the outside pressure round the rotor, cavitation may occur inthe slot space. By establishing communication between the slot space andthe pump space at the back of the vane, as stated above, the pressurebetween the front and back of the vane is equalized, thus eliminatingboth the possible cause of vibrations of the vane in its groove (i.e.sudden pressure fluctuations) and the low pressure in the pump spacebehind the vane.

In the sliding vane pump shown in FIGURES 3, 4 and 5, the groove 9through which the pump space situated in front of the vane 8 is inconstant communication with the slot space 7 situated under the vane, isarranged in one of the slot walls in the same manner as shown in FIGURES1 and 2. The sides or ends of each vane and the ends of the associatedslot are provided with a system of grooves operating in the same manneras the grooves 10 and 11 of the pump shown in FIGURES 1 and 2. Thissystem includes grooves 15 of which one is provided in each side of eachvane 8, and the grooves 16 and 17 in each side of the rotor wall formingeach slot 7.

In this pump the side walls of slots 7 and of the pump spaces are formedby the disk-shaped projections 18 of the rotor 3. Moreover, each groove16 joins a transverse groove 19 (see FIGURE 5) through which each groove16 communicates with the pump space situated behind the associated vane.

In the cross-sectional view of the sliding vane pump represented inFIGURE 3, the shown vane 8 is in the slid-out position. In this case thespace in front of the vane communicates through the groove 9 with theslot space 7. The grooves 15, 16 and 17 are so provided in the ends orsides of the vane 8 and the end walls of slot 7 that in this positionthere is no communication between the slot space 7 and the pump spacebehind the associated vane.

However, when the partition or vane 8 passes one of the dams 12 or 13provided between the outlet port and the inlet port (see FIGURE 4),communication is established between the slot space 7 and the pump spacebehind the associated vane through the grooves 17, 15 and 16 and thetransverse groove 19. At the same time communication is maintainedbetween the slot space 7 and the pump space in front of the associatedvane through the groove 9, so that in the position shown in FIGURE 4 inwhich a vane 8 passes one of the dams 12 and 13 communication isestablished between the spaces in front of and behind the relative vane,thus preventing, as stated above, fluid erosion or attack of the slotspaces, and also wear of the dams. Moreover, wear of the outer edges ofthe vanes is considerably reduced.

It will be understood that the invention is not limited to the shape andposition, nor to the numb-er of grooves establishing the requiredcommunication between the pump spaces on both sides of the vanes in theslid-in positions thereof. Noris the invention restricted to the usethereof in a double-acting pump, as shown in the drawing, but alsoapplies to a single-acting pump as well.

I claim as my invention:

1. A sliding vane pump comprising a housing forming a pump space, inletandoutlet means to said pump space, a rotor rotatably mounted withinsaid housing and having substantially radial slots formed therein,radially slidable vanes carried in these slots of a size whereby slotspaces are formed under said vanes, and fluid conduit means in saidrotor by which each slot space situated under each vane communicates atall times with the pump space which, relative to the direction ofrotation of the rotor, is situated in front of the associated vane,characterized in that each slot space under each vane, the vaneaccommodated in the slot being in the slid-in position, communicateswith the pump space which, relative to the direction of rotation of therotor, is situated behind the associated vane.

2. A sliding vane pump comprising a housing forming a pump space, inletand outlet means to said pump space, a rotor rotatably mounted withinsaid housing and having substantially radial slots formed therein,radially slidable vanes carried in these slots of a size whereby slotspaces are formed under said vanes, and first fluid conduit means insaid rotor by which each slot space situated under each Vanecommunicates at all times with the pump space which, relative to thedirection of rotation of the rotor, is situated in front of theassociated vane, and second fluid conduit means in said rotor by whicheach slot space under each vane, the vane contained in the slot being inthe slid-in position, communicates with the pump space which, relativeto the direction of rotation of the rotor, is situated behind theassociated vane.

3. A sliding vane pump comprising a housing forming a pump space, inletand outlet means to said pump space,

a rotor rotatably mounted within said housing and having substantiallyradial slots formed therein, radially slidable vanes carried in theseslots of a size whereby slot spaces are formed under said vanes, firstfluid conduit means in said rotor in open communication at all timesbetween the slot space under each of said vanes and the pump spacewithin the housing downstream of said vane, and normally closed secondfluid conduit means in said rotor in open communication between the slotspace under each of said vanes and the pump space upstream of said vaneonly when the vane is substantially fully retracted within its slot.

4. A sliding vane pump as claimed in claim 3, wherein the said secondfluid conduit means between the slot spaces and the pump spaces situatedbehind the associated vanes are in the form of grooves which are formedin the vanes and cooperate with other grooves formed in the walls of therelative slots when the vanes are in the slid-in position.

5. A sliding vane pump as claimed in claim 4, wherein the back of eachvane is provided with a substantially radial groove which communicateswith the pump space which, relative to the direction of rotation of therotor, is situated behind the associated vane while the slot wallcooperating with the said vane wall is provided with a groove whichcommunicates with the slot space and communicates with the other grooveonly when the vane is in the slid-in position.

6. A sliding vane pump as claimed in claim 4, wherein at least one ofthe side walls of each slot is provided with two substantially radialgrooves, one of the grooves communicating with the slot space, and theother communicating with the pump space which, relative to the directionof rotation of the rotor, is situated behind the associated vane, whilea substantially radial groove is provided in the side wall of the vanewhich cooperates with the grooved side wall of the slot, which grooveonly communicates with both grooves provided in the side of the slotwhen the vane is in the slid-in position.

References Cited in the file of this patent UNITED STATES PATENTS674,258 Croston May 14, 1901 1,898,914 Vickers Feb. 21, 1933 1,992,848Wade Feb. 26, 1935 2,216,053 Staley Sept. 24, 1940 2,545,238 MacMillinet al Mar. 13, 1951 2,612,114 Ernst Sept. 30, 1952 2,731,919 PrendergastJan. 24, 1956 FOREIGN PATENTS 152,123 Sweden Oct. 25, 1955 689,408France May 27, 1930

